CDMA radio transmission apparatus, CDMA radio reception apparatus, and CDMA radio communication method

ABSTRACT

A CDMA radio transmission apparatus includes a spreader, a chip interleaver, and a transmitter. The spreader divides one symbol to a plurality of N chips equal to a number of a plurality of N slots contained in a frame, by spreading the one symbol by a spreading factor N equal to the number of the plurality of N slots contained in the frame. The chip interleaver performs a chip interleaving processing, whereby each of the plurality of N chips is equally assigned to each of the plurality of N slots. The transmitter operates to transmit the plurality of N slots in sequence.

[0001] This application is a continuation of U.S. patent applicationSer. No. 09/359,020, filed on Jul. 22, 9, pending, the contents of whichare expressly incorporated by reference herein in its entirely.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a CDMA radio communicationsystem and method in a digital radio communication using the CDMA (CodeDivision Multiple Access).

[0004] 2. Description of the Related Art

[0005]FIG. 1 is a block diagram illustrating a configuration of aconventional CDMA radio communication system. In the CDMA radiocommunication system, at a transmission side, transmission data 1 isspread at spreading section 2. The spread signal is modulated atmodulation section 3 and then amplified at transmission amplifyingsection 4. The resultant signal is transmitted from transmissionantenna. An amplitude in transmission amplifier 4 is determined at highrate transmission power setting section 6.

[0006] On the other hand, at a reception side, a signal received atreception antenna is detected at detection section 12 and then despreadat despreading section 13 Received data 14 is thus obtained. Then,received data 14 is subjected to estimation of slot (an interval of fewsymbols) quality at slot quality detection section 16. Based on theestimation result, high rate transmission cower control section 15calculates a control value of high rate transmission power. The controlinformation is transmitted to high rate transmission power settingsection 6 at the transmission side.

[0007] The signals spread at spreading section 2 are configured in orderof symbol as illustrated in FIG. 2. FIG. 2 illustrates an example of thecase of 8 symbols with spreading factor 16. A symbol is composed of 16chips.

[0008]FIG. 3 is a diagram to explain the reception quality in theconventional CDMA radio communication system. FIG. 3 illustrates anexample in which the order of transmitted chips differs between twousers of user A and user B by 5 chips. In addition, fading in each linkis independent.

[0009] With respect to signals of user A, since transmission power iscontrolled at high rate transmission power setting section 6 thatperforms the setting according to an instruction from high ratetransmission power control section 15, the fluctuation of line qualitydue to fading is canceled. Hence, the quality of received data 14 showsan almost constant level as illustrated in FIG. 3. Thus, in the CDMAradio communication system, each user is controlled to transmit a signalin the required minimum transmission power according to the transmissionpower control, in order to decrease the total interference of the systemand improve the system capacity.

[0010]FIG. 4 is a diagram illustrating an interference amount in theconventional CDMA radio communication system. As been understood fromFIG. 4, MS transmission power varies in inverse proportion to the fadingbetween MS and BS_A (hereinafter referred to as fading MS-BS_A. In otherwords, MS transmission power is adjusted to cancel fading MS-BS_A.

[0011] At this point, since the fading between MS and BS_B (hereinafterreferred to as fading MS-BS_B) and fading MS-BS_A are each independent,the interference amount in BS_B that is an other base station varies insuch a manner a large peak appears as illustrated in FIG. 4. Even inthis case, the average value of interference amounts is less than thecase where power transmission control in not performed. It is therebypossible to decrease the total transmission power in the system.

[0012] However, in the conventional CDMA radio communication system,since spread signals are arranged to be concentrated upon a successiveshort time in the same frequency, when the short time is affected byfading and shadowing, qualities of all chips in the time deteriorate atthe same time, resulting in that the qualities are not improved eventhough the spreading gain is obtained by despreading. It thereby resultsin another problem that the system capacity is limited because thetransmission is performed under large transmission power. In addition,in a CDMA-TDD system, since the common frequency is used in forward andreverse links, it is necessary, for example, for a base station tofinish the reverse reception before starting the forward transmission.Therefore, a guard time corresponding to a propagation delay time isrequired with the length limited to ensure the transmission efficiency,thereby resulting in the problem that a cell radius is limited.

SUMMARY OF THE INVENTION

[0013] An object of the present invention is to provide a CDMA radiocommunication system and method which has resistances against fading andshadowing to improve qualities, and in a TDD system, enables a guardtime to be reduced and a cell radius to be extended.

[0014] In the digital radio communication system, in the case where atemporarily long burst error is caused due to affects of, for example,fading, interleaving is performed to decrease the affects to be providedto an error correction decoding section by diffusing the burst error.This interleaving is performed for every slot, and therefore does notcorrespond to fading and shadowing.

[0015] Considering of the aforementioned point, the present inventorsfound out the interleaving of spread chips enables a quality of eachsymbol in a frame to be kept constant, while a rate of transmissionpower control to be alleviated, and achieved the present invention. Itis thereby possible to reduce overhead and decrease interference amountsto other cells.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects and features of the invention willappear more fully hereinafter from a consideration of the followingdescription taken in connection with the accompanying drawing whereinone example is illustrated by way of example, in which;

[0017]FIG. 1 is a block diagram illustrating a configuration of aconventional CDMA radio communication apparatus;

[0018]FIG. 2 is an arrangement diagram of chips in the conventional CDMAradio communication apparatus;

[0019]FIG. 3 is a diagram to explain reception qualities in theconventional CDMA radio communication apparatus;

[0020]FIG. 4 is a diagram to explain interference amounts in theconventional CDMA radio communication apparatus;

[0021]FIG. 5 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 1 of the presentinvention;

[0022]FIG. 6 is an arrangement diagram of chips interleaved in the CDMAradio communication apparatus according to Embodiment 1;

[0023]FIG. 7 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 2 of the presentinvention;

[0024]FIG. 8 is a diagram to explain reception qualities in the CDMAradio communication apparatus according to Embodiment 2;

[0025]FIG. 9 is a diagram to explain interference amounts in the CDMAradio communication apparatus according to Embodiment 2;

[0026]FIG. 10 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 3 of the presentinvention;

[0027]FIG. 11 is a diagram to explain reception qualities in the CDMAradio communication apparatus according to Embodiment 3;

[0028]FIG. 12 is a diagram to explain interference amounts in the CDMAradio communication apparatus according to Embodiment 3;

[0029]FIG. 13 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 4 of the presentinvention;

[0030]FIG. 14 is a diagram to explain reception qualities in the CDMAradio communication apparatus according to Embodiment 4;

[0031]FIG. 15 is a diagram to explain interference amounts in the CDMAradio communication apparatus according to Embodiment 4;

[0032]FIG. 16 is a block diagram illustrating configuration of a CDMAradio communication apparatus according to Embodiment 5 of the presentinvention;

[0033]FIG. 17 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 6 of the presentinvention;

[0034]FIG. 18 is a diagram to explain operations in the CDMA radiocommunication apparatus according to Embodiment 6;

[0035]FIG. 19 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 7 of the presentinvention;

[0036]FIG. 20 is a diagram to explain operations in the CDMA radiocommunication apparatus according to Embodiment 7;

[0037]FIG. 21 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 8 of the presentinvention;

[0038]FIG. 22 is a diagram to explain operations in the CDMA radiocommunication apparatus according to Embodiment 8;

[0039]FIG. 23 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 9 of the presentinvention;

[0040]FIG. 24 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 10 of the presentinvention;

[0041]FIG. 25 is a diagram to explain operations in the CDMA radiocommunication apparatus according to Embodiment 10;

[0042]FIG. 26 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 11 of the presentinvention;

[0043]FIG. 27 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 12 of the presentinvention;

[0044]FIG. 28 is an arrangement diagram of chips subjected to chipinterleaving in the CDMA radio communication apparatus according toEmbodiment 12 of the present invention;

[0045]FIG. 29 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 13 of the presentinvention; and

[0046]FIG. 30 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 13 of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] Embodiments of the present invention will be described in detailin the following with reference to accompanying drawings.

[0048] (Embodiment 1)

[0049]FIG. 5 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 1 of the presentinvention.

[0050] In a transmitter, transmission data 101 is spread at spreadingsection 102, and then subjected to chip interleaving processing at chipinterleaving section 107. The interleaved signal is modulated atmodulation section 103, amplified at transmission amplifying section 104and then transmitted from transmission antenna 105.

[0051] In a receiver, a signal received at reception antenna 111 isdetected at detection section 112, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section 117. The deinterleaveddata is combined at despreading section 113 to obtain received data 114.Further, the slot quality of received data 114 is detected at slotquality detection 116. Based on the detection result, high ratetransmission power control section 115 generates a signal indicative oftransmission power control of high rate to transmit to the transmitter.In the transmitter, based on the control signal, high rate transmissionpower setting section 106 performs transmission power setting of highrate and controls an amplitude for transmission amplifying section 104.

[0052] Operations in the CDMA radio communication apparatus with theabove configuration will be described next.

[0053] Transmission data 101 is spread at spreading section 102, andthen subjected to chip interleaving processing at chip interleavingsection 107. FIG. 6 illustrates an example of chip interleaving. In thisexample, 1 slot contains 8 symbols of spreading factor 16.

[0054] In FIG. 6, symbol 0 is spread to 16 chips. The 16 chips are notarranged serially, but each chip is assigned every 8 chips period.Further, the other 16 chips obtained by respectively spreading symbols 1to 7 are not arranged serially either, but each one is assigned every 8chips period. Accordingly, with respect to chip interleaved spreadsignals, chip (0-1) of symbol 0, chip (1-1) of symbol 1, chip (3-1) ofsymbol 3, chip (4-1) of symbol 4, chip (5-1) of symbol 5, chip (6-1)ofsymbol 6, and chip (7-1) of symbol 7 are assigned in this order.

[0055] According to the aforementioned processing, it is possible toperform the high rate power control capable of following fading. Aspecific example is described using FIG. 3 and FIG. 4. In FIG. 3, whenit is assumed that the spreading factor is 16 and the total symbolnumber is N, 0th chips to 15th chips for symbols 0 to N-1 are assignedrespectively in user A slots 0 to 15 after chip interleaving.

[0056] Qualities do not vary largely in a slot, but vary largely betweenslots, due to user A fading. In this system, since the high ratetransmission power control is performed, the user A signal quality isalmost constant between slots, however is not always constant due tocontrol delay and error when fading occurs rapidly.

[0057] In this embodiment, since the chip interleaving processing isperformed, chips for one symbol are divided to be assigned for aplurality of slots, thereby accepting control delay and error caused byrapid fading. Hence, S/N (signal to noise ratio) is improved byapproximately 12 dB in the case of spreading factor 16 by that spreadchip interleaved signal is deinterleaved and then despread. As a result,variation of qualities between symbols can be reduced. Further, the sameeffect as in user A slot is obtained in user B slot in which five slotsare shifted in the order as compared with user A slots as illustrated inFIG. 3.

[0058] Furthermore, as illustrated in FIG. 4, with respect tointerference in BS_B caused by user A signal due to transmission powercontrol performed by BS_A for user A, the relative value to transmissionpower is not changed as compared to the conventional case. However, theabsolute value is lowered because total transmission power is suppressedwith error correction capability improved by reducing the variation ofqualities between symbols as mentioned above.

[0059] As described above, according to the radio communication systemprovided with the CDMA radio communication apparatus of Embodiment 1, itis possible to decrease total transmission power and thereby increasethe system capacity. This method has effects in down link and highereffects in up link. The reduction of total transmission power furtherallows at the same time achieving of battery saving in a communicationterminal such as a mobile station.

[0060] (Embodiment 2)

[0061]FIG. 7 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 2 of the presentinvention.

[0062] In a transmitter, transmission data 301 is spread at spreadingsection 302, and then subjected to chip interleaving processing at chipinterleaving section 307. The interleaved signal is modulated atmodulation section 303, amplified at transmission amplifying section 304and then transmitted from transmission antenna 305.

[0063] In a receiver, a signal received at reception antenna 311 isdetected at detection section 312, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section 317. The deinterleaveddata is combined at despreading section 313 to obtain received data 314.Further, the slot quality of received data 314 is detected at slotquality detection 116. Based on the detection result, low ratetransmission power control section 315 generates a signal indicative oftransmission power control of low rate to transmit to the transmitter.In the transmitter, based on the control signal, low rate transmissionpower setting section 306 performs transmission power setting of lowrate and controls an amplitude for transmission amplifying section 304.Herein, the low rate transmission power control is a control adaptivenot to rapid variation due to Raleigh fading, but only to slow variationdue to decays caused by distance variation and shadowing, thus making adifference from the high rate transmission power control in thisspecification.

[0064] Operations in the CDMA radio communication apparatus configuredas described above are the same as those in Embodiment 1 except that lowrate transmission power control is performed. In this case, it is notintended to follow fading, but it is intended to perform the low ratetransmission power control capable of following only slow variation suchas distance variation. A specific example is described using FIG. 8 andFIG. 9. In FIG. 8, when it is assumed that the spreading factor is 16and the total symbol number is N, 0th chips to 15 th chips for symbols 0to N-1 are arranged respectively in user A slots 0 to 15 after chipinterleaving.

[0065] Qualities do not vary largely in a slot, but vary largelydepending on slots, due to user A fading. In this system, since the lowrate transmission power control is performed, the difference ofqualities between slots is large. In this embodiment, since the chipinterleaving processing is performed, chips for one symbol are dividedto be assigned for a plurality of slots. Accordingly, chips for onesymbol are arranged both in slots with high signal quality and otherslots with low signal quality. Therefore, the probability that qualitiesof all chips deteriorate is extremely low and qualities with a certainlevel are kept, even though the low rate transmission power control isperformed.

[0066] Since spread chip interleaved signal is deinterleaved and thendespread, it is possible to obtain the improvement effect in the samemanner as in equal gain combining diversity with 16 branches, whiledecreasing fluctuations of qualities between slots. Further, the sameeffect as in user A slot is obtained in user B slot in which five slotsare delayed comparing with user A slots as illustrated in FIG. 8.

[0067] Furthermore, as illustrated in FIG. 9, with respect tointerference in BS_B caused by user A signal, it is possible to decreasea peak interference amount (solid line in FIG. 9) as compared with theinterference in Embodiment 1 (dotted line in FIG. 9). Accordingly, thetransmission does not require excessive power, and thereby it ispossible to decrease total transmission power in the system.

[0068] As described above, according to the radio communication systemprovided with the CDMA radio communication apparatus of Embodiment 2, itis possible to further decrease reduce total transmission power andthereby increase the system capacity. Further, since the peak value oftransmission power control is decreased, it is possible to suppress adynamic range of transmission amplifier and decrease power consumptionand cost.

[0069] (Embodiment 3)

[0070]FIG. 10 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 3 of the presentinvention.

[0071] In a transmitter, transmission data 601 is spread at spreadingsection 602, and then subjected to chip interleaving processing at chipinterleaving section 607. The interleaved signal is modulated atmodulation section 603, amplified at transmission amplifying section 604and then transmitted from transmission antenna 605.

[0072] In a receiver, a signal received at reception antenna 611 isdetected at detection section 612, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section 617. The deinterleaveddata is combined at despreading section 613 to obtain received data 614.Further, the slot quality of received data 614 is detected at slotquality detection 616. Based on the detection result, transmission powerdecrement control section 615 generates a signal indicative oftransmission power decrement control to transmit to the transmitter. Inthe transmitter, based on the control signal, transmission powerdecrement setting section 606 performs transmission power setting andcontrols an amplitude for transmission amplifying section 604.

[0073] Operations in the CDMA radio communication apparatus configuredas described above are the same as those in Embodiment 1 except thattransmission power decrement control is performed. In other words,according to the transmission power decrement control, a transmissiontime is shortened when the transmission is performed with excessquality. As a result, it is possible to transmit a signal in requiredminimum total transmission power.

[0074] A specific example is described using FIG. 11 and FIG. 12. InFIG. 11, when it is assumed that the spreading factor is 16 and thetotal symbol number is N, 0th chips to 15th chips for symbols 0 to N-1are arranged respectively in user A slots 0 to 15 after chipinterleaving. It is further assumed that one frame contains slots 0 to15.

[0075] Qualities do not vary largely in a slot, but vary largelydepending on slots, due to user A fading. In this system, thetransmission power decrement control is performed, in other words, whenthe quality of a frame is higher than a threshold, following signals arenot transmitted. Then, the high rate transmission power control ofEmbodiment 1 or the low rate transmission power control of Embodiment 2is performed until the frame quality of user A exceeds the threshold,and the transmission power is decreased after the frame quality of userA exceeds the threshold.

[0076] For example, as illustrated in FIG. 11, in the case where theslot order difference between user A and user B are 5 slots, when thetransmission power is decreased at the time the user A frame qualityexceeds the threshold, user A signals do not interfere in slots 0 to 4of user B. As a result, it is expected that the user B frame qualityexceeds the threshold faster. Therefore, the transmission power of userB signals is decreased earlier, as a result, the user A frame quality isimproved. Thus, the signal qualities are improved synergistically bymutual transmission power decrement of user A and user B, and it isthereby possible to decrease the system total transmission powerlargely.

[0077] Furthermore, as illustrated in FIG. 12, with respect tointerference in BS_B caused by user A signal, it is possible to decreasea peak interference amount (solid line in FIG. 12) as compared with theinterference in Embodiment 1 (dotted line in FIG. 12) by thetransmission power decrement control performed by BS_A to user A. Stillfurthermore, since it is possible to achieve no transmission power inlatter half of the frame, the total transmission power can be decreased.

[0078] Thus, according to the radio communication system provided withthe CDMA radio communication apparatus of Embodiment 3, it is possibleto further decrease total transmission power and thereby increase thesystem capacity than Embodiment 1 and Embodiment 2.

[0079] (Embodiment 4)

[0080]FIG. 13 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 4 of the presentinvention.

[0081] In a transmitter, transmission data 901 is spread at spreadingsection 902, and then subjected to chip interleaving processing at chipinterleaving section 907 The interleaved signal is modulated atmodulation section 903, amplified at transmission amplifying section 904and then transmitted from transmission antenna 905.

[0082] In a receiver, a signal received at reception antenna 911 isdetected at detection section 912, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section 917. The deinterleaveddata is combined at despreading section 913 to obtain received data 914.Further, the slot quality of received data 914 is detected at slotquality detection section 916. Based on the detection result, inversetransmission power control section 915 generates a signal indicative ofinverse transmission power control to transmit to the transmitter. Inthe transmitter, based on the control signal, inverse transmission powersetting section 906 performs inverse transmission power setting andcontrols an amplitude for transmission amplifying section 904.

[0083] Operations in the CDMA radio communication apparatus configuredas described above are the same as those in Embodiment 1 except thatinverse transmission power control is performed. In an ordinarytransmission power control, transmission power is increased when thequality is low, while is decreased when the quality is high, in order tokeep constant qualities. In the inverse transmission power control,transmission power is increased for signals with high quality, while isdecreased for signals with low quality.

[0084] Under such a control, the signals with high qualities aretransmitted with greater power. In such a case, since the link isadvantageous to transmission, it is possible to improve qualities forsignals with high qualities drastically with a small increment of power.On the other hand, since it is not expected to improve qualities forsignals with low qualities with such increment of power, thetransmission power is increased in order not to interfere in otherusers.

[0085] A specific example is described using FIG. 14 and FIG. 15. InFIG. 14, when it is assumed that the spreading factor is 16 and thetotal symbol number is N, 0th chips to 15th chips for symbols 0 to N-1are arranged respectively in user A slots 0 to 15 after chipinterleaving.

[0086] Qualities do not vary largely in a slot, but vary largelydepending on slots, due to user A fading. In this system where theinverse transmission power control is performed, as illustrated in FIG.14, with respect to signal with high quality (upper part of user Asignal quality), increase of transmission power introduces greatincrease of quality, while with respect to signal with low quality(lower part of user A signal quality), decrease of transmission powerkeeps almost the same quality.

[0087] Qualities do not vary largely in a slot, but vary largelydepending on slots, due to user A fading. In this system, since chipinterleaving is performed, chips for one symbol are divided to beassigned for a plurality of slots. Accordingly, the chips for onesymbols are arranged both in slots with high signal quality and otherslots with low signal quality, the probability that qualities of allchips deteriorate is extremely low, even though the inverse transmissionpower control is performed.

[0088] By that spread chip interleaved signal is deinterleaved and thendespread, it is possible to obtain the improvement effect in the samemanner as in equal gain combining diversity with 16 branches, whiledecreasing fluctuations of qualities between slots.

[0089] In this point, in the case of using the transmission powerdecrement control of Embodiment 3 together, transmission power iscontrolled to be increased as reception quality is higher until user Aframe quality exceeds a predetermined threshold, and to be decreasedwhen user A frame quality exceeds a predetermined threshold. Accordingto the aforementioned processing, since user A signals are transmittedwith higher power in a time period where the quality is high, the signalquality exceeds the threshold earlier than in Example 3. As a result,the transmission power decrement is performed earlier.

[0090] For example, as illustrated in FIG. 14, in the case where theslot order difference between user A and user B are 5 slots, when thetransmission power is decreased at the time the user A frame qualityexceeds the threshold, user A signals do not interfere in slots 0 to 4of user B. As a result, it is expected that the user B frame qualityexceeds the threshold faster. Further, the transmission power decrementis performed earlier than Example 3 by the inverse transmission powercontrol. Therefore, the user A frame quality is further improved, and itis thereby possible to decrease the system total transmission powerlargely. In addition, the total transmission power is decreased eventhough the transmission power decrement control is not performed.

[0091] Furthermore, as illustrated in FIG. 15, with respect tointerference in BS_B caused by user A signal, it is possible to decreasean interference amount (solid line in FIG. 15) as compared with theinterference in Embodiment 1 (dotted line in FIG. 12) by the inversetransmission power performed by BS_A to user A. Still furthermore, sinceit is possible to achieve no transmission power in latter half of theframe by using the transmission power decrement control together, thetotal transmission power can be further decreased.

[0092] Thus, according to the radio communication system provided withthe CDMA radio communication apparatus of Embodiment 4, it is possibleto further decrease total transmission power and thereby increase thesystem capacity than Embodiments 1 to 3.

[0093] (Embodiment 5)

[0094]FIG. 16 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 5 of the presentinvention.

[0095] In a transmitter, transmission data 1201 is spread at spreadingsection 1202, and then subjected to chip interleaving processing at chipinterleaving section 1207. The interleaved signal is modulated atmodulation section 1203, amplified at transmission amplifying section1204 and then transmitted from transmission antenna 1205.

[0096] In a receiver, a signal received at reception antenna 1211 isdetected at detection section 1212, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section 1217. The deinterleaveddata is combined at maximal-ratio despreading section 1213 to obtainreceived data 1214. Maximal-ration despreading section 1213 performsweighting on the deinterleaved data based on likelihood estimated formthe deinterleaved data at likelihood estimation section 1218.

[0097] Further, the slot quality of received data 1214 is detected atslot quality detection section 1216. Based on the detection result,inverse transmission power control section 1215 generates a signalindicative of inverse transmission power control to transmit to thetransmitter. In the transmitter, based on the control signal, inversetransmission power setting section 1206 performs inverse transmissionpower setting and controls an amplitude for transmission amplifyingsection 1204.

[0098] Operations in the CDMA radio communication apparatus configuredas described above are the same as those in Embodiment 4 except thatlikelihood estimation is performed. In other words, likelihoodestimation performed by maximal-ratio despreading section 1213 andlikelihood estimation section 1218 is added to functions of the CDMAradio communication apparatus according to Embodiment 4. It is therebypossible to obtain higher S/N ratio as compared to combining of chipdeinterleaved signals without weighting, enabling better received data1214 to be obtained. The reception quality is thus improved. As aresult, transmission power is decreased and the total transmission poweris thereby further reduced.

[0099] Thus, according to the radio communication system provided withthe CDMA radio communication apparatus of Embodiment 5, it is possibleto further decrease total transmission power and thereby increase thesystem capacity than Embodiments 1 to 4.

[0100] The Embodiments 1 to 5 describe about the case where theinterleaving is performed according to time, however the same effect isobtained in the case where interleaving is performed according tofrequency. Further, it is preferable to combine the embodiments 1 to 5properly to practice.

[0101] (Embodiment 6)

[0102]FIG. 17 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 6 of the presentinvention.

[0103] In a transmitter, transmission data 1301 is spread at spreadingsection 1302, and then subjected to chip interleaving processing at chipinterleaving section(CI) 1307. The interleaved signal is modulated atmodulation section(MOD) 1303, amplified at transmission amplifyingsection(TA) 1304 and then transmitted from transmission antenna 1305.

[0104] In a receiver, a signal received at reception antenna 1311 isdetected at detection section 1312, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section(CD) 1317. Thedeinterleaved data is combined at despreading section 1313 to obtainreceived data 1314.

[0105] Further, an arrival time of received data 1314 is measured atsynchronization detection section(SYNC) 1316. Transmission power controlsection 1315 generates, with respect to a user of which arrival time ina base station communicating with the above-described receiver is late,a control signal for transmission time length and transmission power sothat the reception is completed in a predetermined time and the totaltransmission power is held constant so as to transmit to thetransmitter. In the transmitter, based on the control signal,transmission power setting section(TPS) 1306 performs settings oftransmission time and transmission power and based on the settingvalues, controls an amplitude for transmission amplifying section 1304and transmission time.

[0106] In the CDMA radio communication apparatus configured as describedabove, with respect to a user of which arrival time is late, thetransmission time and transmission power are controlled so that thereception is completed in a predetermined time, while holding the totaltransmission power constant.

[0107] With respect to a user of which arrival time is late, since thetransmission time is determined so that the reception is completed in apredetermined time, the reception time becomes short, and therefore thetransmission power is increased to cancel the effect by the shortreception time. Because transmission signals are subjected to chipinterleaving, the decoding is possible when frame quality with apredetermined level is satisfied even if a part of burst is notreceived.

[0108] A specific example is described using FIG. 18. In FIG. 18, whenit is assumed that the spreading factor is 16 and the total symbolnumber is N, 0th chips to 15th chips for symbols 0 to N-1 are arrangedrespectively in user A slots 0 to 15 after chip interleaving. It isfurther assumed that one frame contains slots 0 to 15.

[0109] In FIG. 18, a first row illustrates operation timing of basestation, a second row illustrates up link transmission timing of user A,and a third row illustrates reception timing of user A transmittedsignal in the base station.

[0110] It is assumed that the signal from user A is not completed in apredetermined time. In this case, as illustrated in a fourth row, thetransmission time length is controlled so that the reception iscompleted in a predetermined time. The transmission time length isdetermined corresponding to the measured arrival time and the operationtiming of the base station. In this point, the transmission power isincreased to transmit under the fixed total transmission power, in orderto compensate the shortening of the transmission time. When thetransmission power is high, since it is expected that the frame qualitywith a predetermined level, necessary for decoding, is satisfied in ashort time, it is possible to complete the reception in a predeterminedtime.

[0111] As described above, according to a radio communication systemprovided with the CDMA radio communication apparatus according toEmbodiment 6, the receiver measures an arrival time of reception data,and with respect to a transmitter having a late arrival time, thetransmission time length is controlled while the transmission power isincreased so that the reception is completed in a predetermined time andthe total transmission power is held constant. Therefore, it is possibleto complete the reception in a predetermined time, while satisfying theframe quality with a predetermined level, necessary for decoding, in ashort time with high transmission power. The aforementioned processingenables all users (transmitters) to complete the receptions in a basestation in a predetermined time.

[0112] (Embodiment 7)

[0113]FIG. 19 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 7 of the presentinvention.

[0114] Operations in a transmitter and a receiver are the same as thosein Embodiment 6 except that transmission time length control isperformed to a user of which arrival time is fast. Based on arrival timeinformation measured from synchronization detection for every user, allusers transmission power control section 1501 (herein after referred toas U-TPC section 1501) controls transmission time lengths of all users.

[0115] Operations in the CDMA radio communication apparatus configuredas described above is described using FIG. 20.

[0116] In FIG. 20, when it is assumed that the spreading factor is 16and the total symbol number is N, 0th chips to 15th chips for symbols 0to N-1 are arranged respectively in user A slots 0 to 15 after chipinterleaving. It is further assumed that one frame contains slots 0 to15.

[0117] In FIG. 20, a first row illustrates operation timing of basestation, a second row illustrates up link transmission timing of user A,and a third row illustrates reception timing of user A transmittedsignal in the base station.

[0118] In addition, it is assumed that the timing in the figure is in areception side. Further, it is assumed that the base station (receiver)communicates with only user A and user B, in order to simplify thedescription. Furthermore, it is assumed that the reception from user Ais completed in a predetermined time in the base station, but thereception from user B is not completed in a predetermined time in thebase station.

[0119] In this case, with respect to user B, it is possible to controlthe reception to be completed in a predetermined time by transmitting inthe same manner as described in Embodiment 6. Further, with respect touser A, the transmission time length is controlled so that the receptionis completed before a following user starts receiving, while thetransmission power is increased in order to compensate the shortening ofthe reception time under the fixed total transmission power.

[0120] As described above, according to a radio communication systemprovided with the CDMA radio communication apparatus according toEmbodiment 6, an interference amount, caused by transmission signalsfrom a transmitter of user A, in transmission signals from a transmitterof user B is reduced. Accordingly, it is possible to decreasetransmission power of user B for satisfying a predetermined framequality than Embodiment 6. It is thus expected that the receptions canbe completed in a predetermined time, while reducing the totaltransmission power for satisfying a predetermined quality for all users.

[0121] (Embodiment 8)

[0122]FIG. 21 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 8 of the presentinvention.

[0123] In a transmitter, transmission data 1301 is spread at spreadingsection 1302, and then subjected to chip interleaving processing at chipinterleaving section 1307. The interleaved signal is modulated atmodulation section 1303, amplified at transmission amplifying section1304 and then transmitted from transmission antenna 1305.

[0124] In a receiver, a signal received at reception antenna 1311 isdetected at detection section 1312, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section 1317. The deinterleaveddata is combined at despreading section 1313 to obtain received data1314.

[0125] Further, an arrival time of received data 1314 is measured atsynchronization detection section 1316. All users transmission startingtime transmission power control section 1701 (hereinafter referred to asUTST-TPC section 1701) generates a control signal for providing a delayin transmission starting time of users having no difference in arrivaltime, and a signal for controlling transmission time length andtransmission power to each user in the same manner as in Embodiments 6and 7.

[0126] Based on the control signals, transmission power setting section1306 sets the transmission time length and transmission power, andtransmission starting time setting section 1702 (herein after referredto as TST-setting section 1702) provides a delay in the transmissionstarting time.

[0127] Operations in the CDMA radio communication apparatus with theconfiguration as describe above is the same as in Embodiment 6 exceptthat control of the transmission starting time is performed.

[0128] In other words, since the transmission starting time control isperformed, it is possible to shift an arrival time intentionally evenwhen there is no difference of arrival time between users, in order toenable interference between users to be reduced. Accordingly,transmission is performed freely with efficiency provided, and furtherflexible control can be performed.

[0129] A specific example is described using FIG. 22. In FIG. 22, whenit is assumed that the spreading factor is 16 and the total symbolnumber is N, 0th chips to 15th chips for symbols 0 to N-1 are arrangedrespectively in user A slots 0 to 15 after chip interleaving. It isfurther assumed that one frame contains slots 0 to 15. In addition, eachtiming in FIG. 22 is a base station side (reception side).

[0130] It is furthermore assumed that user A and user B communicate withthe base station and there is almost no difference between receptiontimings from user A and user B in the base station. In this case, it ispossible to reduce interference by user A in transmission signals foruser B by providing a delay in transmission starting time of user B.

[0131] As described above, according to a radio communication systemprovided with the CDMA radio communication apparatus according toEmbodiment 8, since transmission starting time of a transmitter for eachuser is controlled to be shifted, it is possible to shift an arrivaltime intentionally even when there is no difference of arrival timebetween users, resulting in the reduction of interference between users.Transmission is thus provided with flexibility, and it is therebypossible to transmit signals efficiently.

[0132] (Embodiment 9)

[0133]FIG. 23 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 9 of the presentinvention.

[0134] In a transmitter, transmission data 1301 is spread at spreadingsection 1302, and then subjected to chip interleaving processing at chipinterleaving section 1307. The interleaved signal is modulated atmodulation section 1303, amplified at transmission amplifying section1304 and then transmitted from transmission antenna 1305.

[0135] In a receiver, a signal received at reception antenna 1311 isdetected at detection section 1312, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section 1317. The deinterleaveddata is combined at despreading section 1313 to obtain received data1314.

[0136] Further, with respect to received data 1314, an arrival time ofthe signal is measured at synchronization detection section 1316, andframe quality is measured at frame quality detection section(FQ) 1901.All users power control transmission starting time transmission powercontrol section 1902 (hereinafter referred to as UPCTST-TPC section1902) generates a control signal for providing a delay in transmissionstarting time of users having no difference in arrival time, and asignal for controlling transmission time length and transmission powerand another signal for power control. Operations in CDMA radiocommunication apparatus with the configuration as described above arethe same as in those in Embodiments 6 to 8 except that the power controlis executed.

[0137] In addition, the power control is includes open loop powercontrol, closed loop power control, or combinations of both powercontrols.

[0138] As described above, according to a radio communication systemprovided with the CDMA radio communication apparatus according toEmbodiment 9, it is possible to improve reception qualities by using thepower control for variations due to fading.

[0139] Further, Embodiment 9 provides Embodiment 8 with power control toimprove performance, and it is preferable to apply Embodiment 9 to anyone of Embodiments 6 to 8 to improve respective reception qualities.

[0140] (Embodiment 10)

[0141]FIG. 24 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 10 of the presentinvention.

[0142] In a transmitter, transmission data 1301 is spread at spreadingsection 1302, and then subjected to chip interleaving processing at chipinterleaving section 1307. The interleaved signal is modulated atmodulation section 1303, amplified at transmission amplifying section1304 and then transmitted from transmission antenna 1305.

[0143] In a receiver, a signal received at reception antenna 1311 isdetected at detection section 1312, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section 1317. The deinterleaveddata is combined at despreading section 1313 to obtain received data1314.

[0144] Further, with respect to received data 1314, an arrival time ofthe signal is measured at synchronization detection section 1316, andframe quality is measured at frame quality detection section 1901. Allusers power control transmission discontinuing transmission startingtime transmission power control section 2001 (hereinafter referred to asUPCTDTST-TPC section 2001) generates a control signal for providing adelay in transmission starting time of users having no difference inarrival time, and a signal for controlling transmission time length andtransmission power and another signal for power control.

[0145] In this point, when the detection result of frame qualityindicates a signal which satisfies a predetermined frame quality inrelatively short time as compared to limited transmission time length,the transmission of the signal is discontinued at the time the framequality is satisfied, as illustrated in FIG. 25, because the receptionis performed with excess quality.

[0146] According to the aforementioned processing, it is possible toreduce interference in other users and also reduce the totaltransmission power of a mobile station (transmitter), resulting inbattery saving. Operations in the CDMA radio communication apparatuswith the above configuration as described above is the same as those inEmbodiments 6 to 9 except that transmission is discontinued.

[0147] As described above, according to a radio communication systemprovided with the CDMA radio communication apparatus according toEmbodiment 10, since transmission is discontinued at the time apredetermined frame quality is satisfied in any one of Embodiments 6 to9, it is possible to reduce interference in other users and suppress thetotal transmission power, thereby enabling a mobile station to achievebattery saving.

[0148] Embodiment 10 provides Embodiment 9 with the function ofdiscontinuing transmission, and it is preferable to apply Embodiment 10to any one of Embodiments 6 to 9 in order to reduce both interference inother users and power consumption of mobile station.

[0149] (Embodiment 11)

[0150]FIG. 26 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 11 of the presentinvention.

[0151] In FIG. 26, the configuration is the same as in Embodiment 10except likelihood estimation section(LE) 2201 and maximal-ratiodespreading section(M-R) 2202.

[0152] Transmission data 1301 is spread at spreading section 1302, andthen subjected to chip interleaving processing at chip interleavingsection 1307. The interleaved signal is modulated at modulation section1303, amplified at transmission amplifying section 1304 and thentransmitted from transmission antenna 1305.

[0153] In a receiver, a signal received at reception antenna 1311 isdetected at detection section 1312, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section 1317. The deinterleaveddata is combined at maximal-ratio despreading section 2202 to obtainreceived data 1314.

[0154] Based on likelihood estimated from the chip deinterleaved signalsin likelihood estimation section 2201, maximal-ratio despreading section2202 performs weighting on the signals.

[0155] According to the aforementioned processing, it is possible toobtain higher S/N ratio than in the case of combining without weightingand as a result, received data 1314 is obtained with better qualities.Further with respect to received data 1314, an arrival time of thesignal is measured at synchronization detection section 1316, and framequality is measured at frame quality detection section 1901. Based onthe obtained results, UPCTDTST-TPC section 2001 generates controlsignals for transmission length time with discontinued transmissionconsidered, transmission starting time, transmission power, and powercontrol to transmit to a transmission side.

[0156] Based on the control signals, transmission power setting section1306 performs setting of transmission time length and transmissionpower, and TST-setting section 1702 provides a delay in transmissionstarting time.

[0157] As described above, according to a radio communication systemprovided with the CDMA radio communication apparatus according toEmbodiment 11, since based on likelihood estimated from the chipdeinterleaved signals in likelihood estimation section 2201,maximal-ratio despreading section 2202 combines weighted signals toobtain received data 1314, it is possible to obtain higher S/N ratiothan in the case of combining without weighting, resulting in receiveddata 1314 with better qualities.

[0158] Further, Embodiment 11 provides Embodiment 10 with maximal-rationdespreading section 2202 and likelihood estimation section 2201 toimprove performance, and it is preferable to apply Embodiment 11 to anyconfiguration of Embodiments 6 to 10 in order to enable theconfiguration to improve reception quality.

[0159] (Embodiment 12)

[0160] This embodiment will describe about the case of applying chipinterleaving processing to transmission of control signal in order toshorten a time necessary for a receiver to identify a user of atransmitter using a control signal transmitted from the transmitter ascompared with a conventional radio communication system.

[0161]FIG. 27 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 12 of the presentinvention. In addition, in the following description, control data is toidentify a user of a transmitter and transmitted in burst transmissionfrom the transmitter using a random access channel to request a call.When a receiver detects the control data and identifies the user of thetransmitter, communication is initiated between the transmitter andreceiver.

[0162] In a transmitter, transmission control data 3001 is spread atspreading section 3002, and then subjected to chip interleavingprocessing at chip interleaving section 3003. The interleaved signal ismodulated at modulation section 3004, amplified at transmissionamplifying section 3005 and then transmitted from transmission antenna3006.

[0163] In a receiver, a signal received at reception antenna 3011 isdetected at detection section 3012, and then subjected to inversearrangement to the chip interleaving at the transmission side, i.e.,deinterleaving, at chip deinterleaving section 3013. The deinterleaveddata is combined at despreading section 3014. Data detection section3015 detects the combined data with a predetermined power, and thusreceived control data 3016 is obtained.

[0164] Further, when data detection section 3015 detects data, datadetection section 3015 transmits a signal for notifying transmissioncontrol section 3007 of the detection of data to the transmitter. Whenthe transmitter detects the signal, transmission control section 3007stops modulation section 3304 from operating so as to discontinue thetransmission of control data.

[0165] Operations in the CDMA radio communication apparatus configuredas described above will be described next.

[0166] Transmission control data 3001 is spread at spreading section3002, and then subjected to chip interleaving processing at chipinterleaving section 3003. In this example, the transmission controldata is composed of 8 symbols each containing 1 bit data, i.e., composedof 8 bits. In addition, 1 symbol of control data is spread by spreadingfactor 16.

[0167] In FIG. 28, symbol 0 is spread to 16 chips. The 16 chips are notarranged serially, but each chip is assigned every 8 chips period.Further, the other 16 chips obtained by respectively spreading symbols 1to 7 are not arranged serially either, but each one is assigned every 8chips period. Accordingly, with respect to chip interleaved spreadsignals, chip (0-1) of symbol 0, chip (1-1) of symbol 1, chip (2-1) ofsymbol 2, chip (3-1) of symbol 3, chip (4-1) of symbol 4, chip (5-1) ofsymbol 5, chip (6-1) of symbol 6, and chip (7-1) of symbol 7 areassigned in this order.

[0168] As described above, after spread transmission control data issubjected to chip interleaving, 1st chips to 16th chips for symbols 0 to7 are arranged respectively in slots 1 to 16. Since the chipinterleaving is performed, chips for one symbol are divided to beassigned for a plurality of slots. In other words, slots of spreadcontrol signal each contains information on 8 symbols of transmissioncontrol data with spreading factor 16.

[0169] The transmitter transmits slot 1 of spread control signal to thereceiver in burst transmission with power high enough for the receiverto detect.

[0170] In the receiver, since slot 1 is transmitted with power highenough, data detection section 3015 detects slot 1. Since each slot ofspread control signal contains all information on 8 symbols oftransmission control data, received control data 3016 is obtained at thetime data detection section 3015 detects data of slot 1.

[0171] As described above, according to a CDMA radio communicationsystem provided with the CDMA radio communication apparatus ofEmbodiment 12, each slot of spread control signal contains allinformation for identifying a user of a transmitter, the receiver canidentify the user of the transmitter when detects a slot which istransmitted first from the transmitter. Accordingly, as compared to aconventional radio communication system in which a transmitter transmitseach symbol of transmission control data in one slot, and a receiverneeds to receive all the slots to identify a user of the transmitter, itis possible to improve transmission efficiency of transmission controldata and shorten a time necessary for the receiver to identify the userof the transmitter. Further, since the transmitter discontinuestransmitting control data at the time the receiver detects the controldata, it is possible to reduce power consumption of the transmitter.

[0172] (Embodiment 13)

[0173] Embodiment 13 will describe the case where chip interleaving isapplied to transmission of control data in order to shorten a timenecessary for a receiver to identify a user of a transmitter as comparedwith a conventional radio communication system, when the transmittertransmits control data as increasing power gradually to prevent thepower from causing interference in users of other transmitters.

[0174]FIG. 29 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 13. The basicconfiguration and operations in the radio communication apparatus ofEmbodiment 13 are the same as those in Embodiment 12 except that basedon a detection signal in data detection section 3015, transmission powersetting section 3008 controls an amplitude in transmission amplifyingsection 3005. Therefore, the different points are only explained below.

[0175] Transmission power setting section 3008 controls the amplitude intransmission amplifying section 3005 to be increased when a signal fornotifying of data detection is not transmitted from data detectionsection 3015.

[0176] Operations in the CDMA radio communication apparatus configureddescribed above will be described next. The transmitter transmits slotsof spread control signal illustrated in FIG. 28 in the order from slot 1to the receiver in burst transmission. The transmitter transmits slot 1with power low enough to prevent the signal from causing interference inusers of other transmitters.

[0177] When data detection section 3015 in the receiver does not detectdata because the power of slot 1 data which is combined in despreadingsection 3014 is low, transmission power setting section 3008 controlsthe amplitude in transmission amplifying section 3005 to be increased.Slot 2 is thereby transmitted with higher power than slot 1 from thetransmitter.

[0178] As described above, as the transmitter performs amplitudecontrol, when power of data combined in despreading section 3014 in thereceiver reaches a predetermined level, the receiver detects the data indata detection section 3015. Since each slot of spread control signalcontains all information on 8 symbols of transmission control data,received control data 3016 is obtained at the time data detectionsection 3015 detects the data.

[0179] As described above, according to a CDMA radio communicationsystem provided with the CDMA radio communication apparatus ofEmbodiment 13, each slot of spread control signal contains allinformation for identifying a user of a transmitter, the receiver canidentify the user of the transmitter when detects a slot with apredetermined power level. Accordingly, it is possible for a transmitterto increase transmission power for every one slot for each symbol oftransmission control data and for a receiver to identify the user of thetransmitter when the receiver detects a slot with a predetermined powerlevel and then receives all slots in the predetermined power level.Therefore, as compared to a conventional radio communication system inwhich a transmitter needs to retransmit a slot, of which power dose notreach a predetermined level, in the predetermined level, thetransmission efficiency of transmission control data is improved, andthereby it is possible to reduce the time necessary for the receiver toidentify the user of the transmitter. Further, since the transmitterdiscontinues transmitting control data at the time the receiver detectsthe control data, it is possible to reduce power consumption of thetransmitter.

[0180] (Embodiment 14)

[0181] Embodiment 14 will describe a CDMA radio communication apparatusof which a receiver stores control data with less power than apredetermined level sequentially in a buffer in order to shorten a timefor a receiver to identify a user of a transmitter.

[0182]FIG. 30 is a block diagram illustrating a configuration of a CDMAradio communication apparatus according to Embodiment 14. The basicconfiguration and operations in the radio communication apparatus ofEmbodiment 14 are the same as those in Embodiment 13 except that datacombined at despreading section 3014 is stored in buffer section 3017,and data detection section 3015 detects data based on power of combineddata stored in buffer section 3017. Therefore, the different points areonly explained below.

[0183] The receiver stores data of slot 1 combined at despreadingsection 3014 in buffer section 3017. When data detection section 3015fails to detect the data because power of stored slot 1 data is low,transmission power setting section 3008 controls an amplitude intransmission amplifying section 3005 to be increased. The transmitterthereby transmits slot 2 with higher power than slot 1.

[0184] The receiver stores data of slot 2 combined at despreadingsection 3014 in buffer section 3017. Accordingly, data of slot 1 andslot 2 are stored in buffer section 3017, as a result, power of datacorresponds a sum of both data power.

[0185] As described above, combined data is stored in buffer section3017 sequentially. When the sum of power of combined data stored inbuffer section 3017 reaches a predetermined power level, data detectionsection 3015 detects the data, and thus received control data 3016 isobtained.

[0186] As described above, according to a radio communication systemprovided with the radio communication apparatus of Embodiment 14, as thereceiver stores control data with less power than a predetermined levelsequentially, when the sum of power of control data stored in the bufferreaches the predetermined level, the receiver detects the control dataand identifies a user of a transmitter.

[0187] Accordingly, since the receiver can not detect a slot until thepower reaches the predetermined level, a smaller number of transmissionslot is enough than Embodiment 13 in which waste is caused byretransmission of slot with less power than the predetermined level.Therefore, transmission efficiency of transmission control data isfurther improved, and it is thus possible to shorten the time necessaryfor the receiver to identify the user of the transmitter. Further, it ispossible to reduce power consumption of the receiver.

[0188] The present invention solves the problem that a desired qualityis not satisfied even if spreading gain is obtained in the case wherequalities of all the spread chips deteriorate concurrently due to fadingor shadowing. Further, it is thereby possible to reduce the totaltransmission power and improve the system capacity. Furthermore, it ispossible to reduce mutual interference amounts in signals of a pluralityof users, which is a basic reason for limiting a capacity in the CDMAsystem, thereby enabling the system capacity and battery saving in amobile station both to be improved. Still furthermore, it is possible inthe TDD system to shorten a guard time and extend a cell radius.

[0189] The present invention is not limited to the above describedembodiments, and various variations and modifications may be possiblewithout departing from the scope of the present invention.

[0190] This application is based on the Japanese Patent Applications No.HEI10-209911 filed on Jul. 24, 1998, No.HEI11-091429 filed on Mar. 31,1999 and No.HEI11-094269 filed on Mar. 31, 1999, entire contents ofwhich are expressly incorporated by reference herein.

We claim:
 1. A CDMA radio transmission apparatus, comprising: aspreading system that divides one symbol to a plurality of N chips equalto a number of a plurality of N slots contained in one frame, byspreading said one symbol by a spreading factor N equal to the number ofthe plurality of N slots contained in the one frame; a chip interleavingsection that performs chip interleaving processing whereby each of theplurality of N chips is equally assigned to each of the plurality of Nslots; and a transmission section that transmits the plurality of Nslots in sequence.
 2. The CDMA radio transmission apparatus according toclaim 1, further comprising a control section that performs a low ratetransmission power control to the plurality of N slots, the low ratetransmission power control being adaptable to at least one ofattenuation caused by distance variation and shadowing.
 3. The CDMAradio transmission apparatus according to claim 1, further comprising adecreaser that decreases the transmission power of the plurality of Nslots when the quality of received data at a CDMA radio receptionapparatus exceeds a threshold.
 4. The CDMA radio transmission apparatusaccording to claim 1, further comprising a control section that controlsthe transmission power of the plurality of N slots such that thetransmission power is increased as a quality of the received data at aCDMA radio reception apparatus increases, and is decreased as thequality of the received data at the CDMA radio reception apparatusdecreases.
 5. A CDMA radio transmission apparatus according to claim 1,further comprising: an amplitude controller that controls an amplitudeto gradually increase a transmission power of the plurality of N slots;and a transmission controller that discontinues slot transmission when areception level of a slot received in a CDMA radio reception apparatusexceeds a threshold.
 6. A CDMA radio reception apparatus, comprising: areception section that receives in sequence a plurality of N slots, toeach of which each of a plurality of N chips equal to a number of theplurality of N slots is equally assigned, the plurality of N chipsobtained by spreading one symbol by a spreading factor N equal to thenumber of the plurality of N slots contained in one frame in a CDMAradio transmission apparatus; and a chip deinterleaving section thatperforms chip deinterleaving processing on the plurality of N chips. 7.The CDMA radio reception apparatus according to claim 6, furthercomprising a likelihood estimator that performs likelihood estimation ondata subjected to chip deinterleaving processing.
 8. The CDMA radioreception apparatus according to claim 6, further comprising: a leveldetector that detects a reception level of data subjected to the chipdeinterleaving processing; and a judgment section that performs athreshold judgment on the detected reception level and instructs theCDMA radio transmission apparatus to discontinue slot transmission whenthe detected reception level exceeds a threshold.
 9. The CDMA radioreception apparatus according to claim 6, further comprising: a leveldetector that detects a reception level of data subjected to the chipdeinterleaving processing; an adder that adds the detected receptionlevel; and a judgment section that performs a threshold judgment on theadded reception level and instructs the CDMA radio transmissionapparatus to discontinue slot transmission when the added receptionlevel exceeds a threshold.
 10. A CDMA radio communication method,comprising: dividing one symbol to a plurality of N chips equal to anumber of a plurality of N slots contained in one frame, by spreadingsaid one symbol by a spreading factor N equal to the number of theplurality of N slots contained in the one frame; performing chipinterleaving processing whereby each of the plurality of N chips isequally assigned to each of the plurality of N slots; and transmittingthe plurality of N slots in sequence.
 11. A CDMA radio communicationmethod, comprising: receiving in sequence a plurality of N slots, toeach of which each of a plurality of N chips equal to a number of theplurality of N slots is equally assigned, the plurality of N chipsobtained by spreading one symbol by a spreading factor N equal to thenumber of the plurality of N slots contained in one frame in a CDMAradio transmission apparatus; and performing chip deinterleavingprocessing on the plurality of N chips.